Compositions comprising sun protection agents (embracing all different names such as sunscreen, sun or solar filter, sun block, antisun, photo protector and similars), are topical products aimed at interacting—e.g. absorbing or reflecting—with solar radiation incident on the skin or hair. Concerning the skin, the use of such compositions help protect against a number of various deleterious effects of radiation upon the skin, such as sunburn, premature ageing, wrinkles, loss of elasticity, photodermatitis and cancer.
In the text that follows, “skin products” or “sun protection products” are to be understood as aimed at be applied to skin or hair, irrespectively of the intended use, such as cosmetic, cosmeceutical or medical.
Different sun protection agents comprised in skin products have different ways of dealing with the sun light in order to provide “sun protection”, e.g. by chemically absorbing the radiation or by physically blocking out the radiation.
In the following text, “sun protection products” is indicative of both, products that aim specifically at providing sun protection, as well as multi-functional products such as anti-ageing, face or body treatment products, make-up, shampoo, etc., that comprise as an additional benefit ingredient a sun protection agent.
Sun protection compositions are often presented as emulsions, be it of oil-in-water type (i.e. a cosmetically and/or dermatologically acceptable support consisting of an aqueous dispersing continuous phase and of a fatty dispersed discontinuous phase), or water-in-oil type (aqueous phase dispersed in a continuous fatty phase), which contain, in varying concentrations, one or more standard lipophilic organic screening agents and/or metal oxide mineral nanopigments capable of selectively absorbing/reflecting harmful UV radiation, such screening agents (and the amounts thereof) being selected as a function of the desired sun protection factor (SPF). Such ingredients are not known to provide relevant protection against IR radiation.
A list with non-limitative examples of additives in sun protection products that chemically absorb UV radiation is as follows: aminobenzoic acid, avobenzone, benzophenone, cinoxate, dioxybenzone, ensulizole, homosalate, meradimate, octisalate, octinoxate, octocrylene, PABA (p-amino benzoic acid), sulisobenzone, trolamine salicylate.
A list with non-limitative examples of additives in sun protection products that physically block out UV radiation comprises the following metallic oxides: iron, titanium, cerium, zinc, aluminum, zirconium and silicon.
While most sun protection products screen out only UV-B rays, exposure to UV-A and IR radiations are responsible for premature ageing of the skin, including loss of elasticity of the skin and wrinkles. So the search for efficient wide spectrum radiation filters is an ongoing activity in the sun protection industry.
According to one aspect of the invention, cyclodextrin employed in a composition along with one or more UV radiation absorbers and/or one or more UV radiation blockers boosts their UV-protection effect. According to another aspect of the invention, cyclodextrin employed in a composition, alone or with one or more UV radiation absorbers and/or one or more UV radiation blockers provides IR-protection effect.